Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
from queue import Queue
h,w=map(int,input().split())
S=[list(input()) for _ in range(h)]

memo=[[-1]*w for _ in range(h)]
def bfs(q):
  x,y,cnt=q.get()
  if x<0 or x>=w or y<0 or y>=h:
    return
  elif S[y][x]=='#':
    return
  elif memo[y][x]<0:
    memo[y][x]=cnt
    q.put([x-1,y,cnt+1])
    q.put([x+1,y,cnt+1])
    q.put([x,y-1,cnt+1])
    q.put([x,y+1,cnt+1])

q=Queue()
q.put([0,0,0])
while not q.empty():
  bfs(q)
if memo[h-1][w-1]==-1:
  print(-1)
  exit()
cnt=0
for i in range(h):
  cnt+=S[i].count('.')
print(cnt-memo[h-1][w-1]-1)